Logic Circuit With Tapped Collector Load Resistor
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
This circuit is a common diode-transistor logic (DTL) circuit, with impedance Z added. All remaining components form a standard DTL circuit. Impedance Z creates a feedback circuit between the collector output and the base. The voltage at the junction of RB and RC varies dynamically as the input voltage changes, therefore reducing the power consumed by the circuit. In addition, since the logic high output level is reduced, the propagation delay of the circuit is reduced. Impedance Z can be linear or nonlinear. We have used both a resistor and a Schottky barrier diode successfully. Use of a nonlinear impedance can improve circuit performance by dynamically changing the amount of feedback as a function of the input voltage.